Everybody loves green. What's the word of the moment?

Ask any architect, builder or engineer about key building trends around the world, and they’ll almost certainly say sustainable, eco designs are where things are headed.

And that’s a perfect fit with EXPAN timber buildings – using raw material sourced from renewable, commercial plantation forests. So how, exactly, is using timber in the construction of modern buildings good for the environment, and how does it reduce greenhouse gas (GHG) emissions? Here’s the lowdown.

Conventional long-span and multi-storey buildings use concrete or steel as structural materials. A recent study for the Ministry of Agriculture and Forestry (MAF) on the new six-storey Biological Sciences building at University of Canterbury showed that EXPAN buildings that use massive timber members - substituting a significant amount of conventional structural concrete and steel with engineered wood product (EWP) components - provide environmental benefits that are tangible, measureable and long-term.

EXPAN timber buildings - good for the environment, how?

The raw timber for EXPAN buildings is sourced from carefully managed, renewable, commercial plantation forestry, which meets stringent environmental standards and certification and contributes significantly to supporting local communities.

While EXPAN buildings use a lot of structural timber, overall they can make huge savings in quantities of materials to provide buildings which are light-weight, with significantly reduced concrete foundations. The MAF study showed that EXPAN timber buildings had the lowest initial embodied energy and lower initial embodied CO2 equivalent for materials and, over the full 60-year lifetime of the buildings, the lowest total primary energy use and the lowest global warming potential (GWP).

Life Cycle Assessment (LCA) shows that EXPAN timber buildings are good for the environment because;

• Both the initial and full lifecycle carbon footprint of an EXPAN building is less than an equivalent concrete or steel building.• The timber in each building stores carbon, much of which is removed from the atmosphere permanently, even after the demolition of the building;• State-of-the-art EXPAN buildings have low (on-going) energy consumption during the entire cycle of occupancy and operation• The timber used in EXPAN buildings is a continuously renewable, sustainable resource.

EXPAN timber buildings - lowest carbon footprint, why?

Recent comparative studies indicate that the carbon footprint of a multi-storey engineered timber building over its full lifetime (including its operational phase and all operational energy use, and end-of-life) is around 1.69 tonnes CO2 eq. / m2 - more than 13% less than the carbon footprint of the same building constructed from steel.

When it comes to the carbon footprint of materials only (embodied carbon), increased use of timber in the timber building leads to considerably lower net CO2 eq. emissions than concrete and steel buildings.

Advances in technologies and policy changes both here, and internationally, will mean that in the future there will be more importance placed on secure disposal, recycling and reusing deconstructed building materials, as well as being able to burn timber waste to recover energy. This will significantly reduce net carbon emission back to the atmosphere and will lead to an even greater improvement in the lifetime footprint of timber materials and timber buildings relative to concrete and steel.